Abstract: The Earth offers a multitude of modeling challenges, from the dynamics of the atmosphere and oceans, to the melting of the polar ice caps. To understand and model these climate processes, a wide range of mathematics is needed, such as differential equations, multiscale modeling, and stochastic processes. In this minisymposium, the presentations span a broad range of climate processes and mathematical areas, and will be accessible to a more general audience. They include a blend of modeling, experiments, and data analysis, and demonstrate how mathematics is being employed to address fundamental problems of climate science.

MS-Tu-D-07-113:30--14:00Modeling the Melt: What Math Tells us About the Shrinking Polar Ice CapsGolden, Kenneth (Univ. of Utah)Abstract: The precipitous loss of Arctic sea ice has far outpaced expert predictions. We will discuss how mathematical models of composite materials and statistical physics are being used to study key sea ice processes and advance how sea ice is represented in climate models. This work is helping to improve projections of the fate of Earth's ice packs, and the response of polar ecosystems.

MS-Tu-D-07-214:00--14:30A Minimal Model for Precipitating ConvectionSmith, Leslie (Univ. of Wisconsin, Madison)Abstract: We consider a minimal model of precipitating, turbulent convection. Cloud microphysics is included assuming fast condensation, auto-conversion and evaporation. The conservation laws for momentum, energy, moist entropy, and total water are retained in simple nontrivial form. We demonstrate that the model is able to capture general features of tropical squall lines. Linear stability analysis in a saturated environment predicts that the unstable scales depend on rainfall speed, a feature not captured by parcel theory.

CP-Tu-D-07-414:50--15:10Acceleration of a High Order CFD solver with Optimized OpenACC directivesGong, Jing (KTH Royal Inst. of Tech.)Abstract: Nek5000 is an open-source code for the simulation of incompressible flows. Nek5000 is widely used in a broad range of applications, including the study of thermal hydraulics in nuclear reactor cores, the modeling of ocean currents and the simulation of combustion in mechanical engines.
We have previously introduced a case study of partially porting to parallel GPU-accelerated systems using OpenACC. In this presentation, we follow on from our previously developed work and take advantage of the optimized results to port the full version of Nek5000 to GPU-accelerated systems. The presentation focuses on porting and optimizing the most time-consuming parts of Nek5000 to the GPU systems, namely the matrix-matrix multiplication and the preconditioned CG linear solvers. The gather-scatter method with MPI operations is redesigned to decrease the amount of data transferred between the host and accelerator.